Latch attachment for an electromagnetically operated switching device



.IPEREZ March 17, 1970 A. M

LATCH ATTACHMENT FOR AN ELEGTRO-MAGNETICALLY OPERATED swx'rcnme DEVICE Filed Oct. 14, 1968 FIG.2

FIG.3

INVENTOR.

ADOLFO M. PEREZ O 2 8 r a l 470% M o m 3 w 5w M n 3 w w 7 2 ll 6 8 4 r 5 5 D m 8 l 2 I l 7 O Q H O M 5 8 3 4 1;: 6 0 6 8 O 7 4 O 6 6 6 9 6 7 m 3 7 2 m United States Patent 3,501,721 LATCH ATTACHMENT FOR AN ELECTRO- MAGNETICALLY OPERATED SWITCHING DEVICE Adolfo M. Perez, Racine, Wis., assignor to Square D Company, Park Ridge, III., a corporation of Michigan Filed Oct. 14, 1968, Ser. No. 767,344 Int. Cl. H01h 9/24 U.S. Cl. 335170 11 Claims ABSTRACT OF THE DISCLOSURE A latch attachment for an electromagnetically operated switching device, such as a relay or a contactor. The latch attachment includes a means for assuring that the lath mechanism within the attachment is de-activated when the attachment is initially installed on the switchingdevice.

This invention relates to electromagnetic devices, and more particularly, to an electromagnetic or manually releasable latch attachment that is adapted to be attached to an electromagnetically operated switching device for latching the movable parts of the switching device in an energized position.

Mechanically held contactors, relays and the like, are electromechanical devices which provide a safe and convenient means for switching circuits where requirements demand continuity of circuit connection or absolute quietness of operation. Circuit continuity during power failures is often important in automatic processing to insure that a sequence of operation will continue from the point of interruption after power is resumed. Absolute quietness of operation is many times required when it is necessary for a contactor to operate in hospitals, schools or office buildings. Mechanically held contactors are generally applied in locations where the slight hum, characteristic of A.C. magnetic devices, is objectionable.

Conventionally, relays, contactors and the like are furnished as basic switching units and when a mechanically held function is required, a latch attachment is secured to the basic switching unit to maintain the contacts in one condition (e.g., either open or closed), when the operating coil of the basic switching unit is de-energized. While the several types of mechanisms used for this purpose have been found generally satisfactory, they have been wanting in that unless they are properly applied to the basic switching unit, the attachment may cause the contacts of the switch to be held in a mechanically held condition before the basic switch has been initially energized to operate its switching contacts. Thus, for example, if the latch attachment, when initially secured to the basic switching unit to maintain the contacts in basic switch to be held in a circuit closing position when they are expected to be in a circuit opening condition, damage and injury to equipment and personnel may result when the power to the system, wherein the basic switch unit is included, is initially turned on.

It is an object of the present invention to provide an improved latching mechanism in a latch attachment for an electromagnetically operating switching device which will cause the latching mechanism to be released when the attachment is separated from the switching device.

Another object is to provide a latch attachment for an electromagnetically operated switching unit with a means which will de-activate the latching mechanism of the attachment when the attachment is separated from the switching device.

A further object is to provide an improved latching mechanism in a latch attachment for a basic switching unit which after having performed a latching operation 3,501,721 Patented Mar. 17, 1970 is releasable either manually or electromagnetically and which includes a means for maintaining the latching mechanism in a released condition prior to the attachment of the latching mechanism on the basic switching unit.

An additional object is to provide a latch attachment for an electromechanically operated switching device with a means which will prevent the latch attachment from causing the contacts of the switching device from being held in a circuit closing condition when the attachment is initially secured on the switching device.

Further objects and features of the invention will be readily apparent to those skilled in the art from the specification and appended drawing illustrating certain preferred embodiments in which:

FIG. 1 is a top plan view of a latch attachment incorporating the features of the present invention.

FIG. 2 is a cross sectional view generally along line 22 in FIG. 1 showing the latch attachment incorporating the present invention as mounted on an end of an electromagnetically operated switching device.

FIG. 3 is a view partly in cross section of a latching member as used in the latch attachment in FIG. 2.

Referring to FIG. 2 of the drawings, a basic electromechanically operated switching device 10 includes a housing 11 having an end 12 carrying a mounting plate which is securable by suitable screws to a mounting panel 16. The housing 11 has an end 18 to which an electromagnetically operated latching device 20 incorporating the present invention is secured. The illustrated switching device 10 is fully disclosed in a U.S. Patent 3,354,415 which was granted on Nov. 21, 1967 to the inventors Joseph J. Gribble, Kenneth J. Marien and Harold E. Whiting. The Gribble et al. patent also discloses a latch attachment as may be used with the switching device 10. While the latching attachment as disclosed in the Gribble et al. patent provided satisfactory service, it was discovered that it included an objectionable feature in that if the latch attachment was secured to the basic switching device when the latch mechanism was held in the latching condition, the circuit closing contacts of the switching device would be held closed. Normally this condition would be detected by visual inspection ofthe installation. However, if inadvertently the condition escaped detection and the switching device were wired in circuit with a conventional disconnect switch, initial closure of the disconnect switch could result in an unexpected energization of the electrical load controlled by the switching device and possible injury or damage to personnel and equipment.

As shown in FIG. 2 and fully disclosed in the Gribble et al. patent, the switching device 10 includes movable contact carrier 22 which when moved from a de-energized position, not shown, to energized position shown in FIG. 2, will position a plurality of movable contacts, not shown, in a circuit closing position with stationary contacts that are electrically connected to wire connecting terminal members designated by a numeral 24 in FIG. 2.

The movable contact carrier 22 is arranged to move in a plane perpendicular to the ends 12 and 18 and is biased by springs, not shown, to the released position so an end 26 of the contact carrier 22 is adjacent the end 18 of the housing 11.

When the switching device 10' is used as a basic switching unit per se, the end 18 of the housing 11 for the switching device 10 is closed by a cover, not shown. When the switching device 10' is required to provide a mechanically held function, the latching device, which replaces the cover, is secured to the end 18 by suitable screws which pass through a pair of openings 28 in a housing 30 for the latching device 20 and are threaded into inserts within the housing 11.

The housing 30 has a bottom surface 32 corresponding in shape to the replaced cover and encloses a cavity 33 wherein an electromagnet 34, a latching member 36, and a latching lever 38 are positioned. The electromagnet includes a magnet coil 40' which is connectible in an energizing electric circuit through a pair of terminals 42 which are external of the housing 30'. The coil 40 has a central bore which receives a magnet core 44 that is adapted to be magnetized upon energization of the coil 40. The magnet core 44 is positioned in the bore of the coil 40 by a U-shaped yoke 46 which is secured to a U-shaped member 48. The coil 40, the yoke 46, the member 48 and the core 44 when positioned as shown in FIG. 2, are maintained assembled when the yoke 46 and the member 48 are welded together at the areas indicated by a numeral 50. Slida-bly positioned within the bore in the coil 40' and guided therein by a bearing 52 is a plunger assembly which includes an armature 54, which is attracted to engage the magnet core 44 when the coil 40 is energized, and a plunger 56 which extends through a bore in the magnet core 44 to present a stem 58 which extends externally of the magnet core 44.

Thelatching lever 38 is bell-crank like in shape and is rotatable about a pivot 60 which is provided by the housing 30. The latching lever 38 has an arm portion 62 extending to be engaged by the end of the stem 58 and an arm portion 64 which extends through an opening 66 in a top wall 67 in the housing 30. Extending downwardly at an angle to the arm portion 62 is an arm 68 which has a downwardly facing free edge which provides a latching surface 70. A spring 72 reacting between an inner top wall of the cavity within the housing 30 and the arm 62 constantly urges the latching lever 38 in a clockwise direction toward a latching position illustrated in FIG. 2.

The latching member 36 is formed as an assembly of two parts 74 and 76 which are resiliently positioned relative to each other by a spring 78 and an adjusting screw 80. The spring 78 is positioned between the parts 74 and 76 and the adjusting screw '80 has a head portion 82 engaging the part 74 so that a threaded portion 84 may pass with clearance through a bore 86 in the part 74 through the convolutions of the spring 78 and be threaded into an opening in the part 76. The part 76 is guided for movement between a latching position shown in FIG. 2 and a released position by a guideway 87 in the housing 30 that extends from an opening in the bottom surface 32 so a free end '88 on the part 76 engages the end 26 of the contact carrier 22. The part 74 has a ledge or latching surface 90 facing upwardly toward and disposed to be engaged by the latching surface 70 on the latching lever 38 when the movable contact carrier 22 is positioned so that the movable contacts of the switching device are pressed into tight engagement with the stationary contacts. Extending downwardly below the latching surface 90 is a vertical surface 92 which is engaged by the free end which provides the latching surface 70 when the latching lever including the part 74 is moved upwardly to a released position wherein the movable contacts of the switching device 10 are separated from the stationary contacts. The arrangement including the spring 78 and the screw 80 is provided to adjustably locate the position of the latching surface 90 relative to the latching surface 70 when the latching member 36 and the latching lever 38 are in the latched position and to properly locate the position of the free end 88 relative to the free end 26 when the contact carrier 22 is in the position wherein the movable contacts are in tight engagement with the stationary contacts of the switching device 10. The spring 78 has a compressive resistance which exceeds the force which urges the contact carrier 22 upwardly to a position wherein the movable contacts of the switching device 10 are separated from the stationary contacts. The latching member 36 is constantly urged toward the latching position shown in FIG. 2 by a spring 94 which is positioned between the inner top wall of the housing 30 and the part 74. The spring 94 has a resistance to compression which is less than the force urging the contact carrier 22 upwardly.

While not shown, if required, a suitable switch may be included within the housing 30 to be operated on movement of the latching member 36 and the latch lever 38 to the latching position. The switch will operate contacts and open a circuit between a pair of terminals 96 and 98 that are in series with the energizing winding of the coil of the switch device 11. Thus the energizing circuit for the coil within the switching device 11 will be interrupted while the contacts thereof are held closed by the latching device 20.

The energization of the electromagnet within the switching device 10 causes the contact carrier 22 to move downwardly in the direction of the mounting panel 16. The spring 94 causes the latching member 36 to follow the movement of the contact carrier 22 and the vertical surface 92 to pass along the latching surface 70 as the latching member 36 moves to a position shown in FIG. 2. When the latching member 36 is positioned as shown in FIG. 2, the force of the spring 72 causes the latching lever 38 to rotate in a clockwise direction to a latching position wherein the latching surfaces 70 and are aligned with each other to prevent upward movement of the latching member 36 and the contact carrier 22 when the electromagnet within the switching device 10 is deenergized.

The latching function provided by the latching device 20 may be released either manually or electromagnetically. The release is accomplished manually by applying a suitable force on the arm 64 to rotate the latching lever 38 in a counterclockwise direction about its pivot 60 to a position wherein the latching surface 70 is disengaged from the latching surface 90. When the surfaces 70 and 90 are thus disengaged, and the switching device is de-energized, the force exerted on the contact carrier 22 by a spring within the switching device 10 will cause the contact carrier 22 and the latching member 36 to move upwardly to a position wherein the spring 94 is compressed and the latching surface 70; is positioned to engage the vertical surface 92 when the manual force on the arm 64 is removed.

The release of the latching device may be accomplished electrically by momentarily energizing the coil 40. When the coil 40 is energized, the armature 54 and the plunger 56 move upwardly to a position wherein the armature 54 engages the magnet core 44. The movement of the plunger 56 causes the latching lever 38 to rotate counterclockwise against the force of the spring 72 to a position wherein the latching surfaces 70 and 90 are disengaged so that the contact carrier 22 and latching member 36 may move upwardly in the same manner as when the latching device 20 was released manually. After the latching surfaces 70* and 90 are disengaged and the latching member 36 has moved upwardly to a position wherein the vertical surface 92 is aligned with the latching surface 70, the coil 40 may be de-energized without affecting the upward movement of the contact carrier 22 and the latching member 36 to the position wherein the spring 94 is compressed and the contact carrier 22 is positioned so that the movable contacts are separated from the stationary contacts within the switching device 10.

When the latching device 20 is detached from the switching device 10, the latching member 36 and the latching lever 38 are biased to moved by the springs 94 and '72 to a latching position wherein the latching surfaces 70 and 90 are positioned to engage each other. A release means 100 including a pin 102, a lever 104 and a spring 106 is Provided to move the latching lever 38 to a released position when the latching device 20 is detached from the switching device 10. The pin 102 is supported by the housing 30 and provides a pivot for the lever 104. The lever 104 is rotatably mounted on the pin 102 to have an arm portion 108 engageable with a bottom sur-.

face 110 of the armature 54 and an arm portion 112 engageable with a surface portion of the end 18 of the switching device when the latching device 20 is mounted on the switching device 10. The spring 106 is of the torsion type, having convolutions surrounding the pin 102 and an arm 114 engaging a bottom edge of the yoke 48 and an arm 116 hooked over the arm 108 of the lever 104. The spring is arranged to urge the arm 108 into engagement with the surface 110 of the armature and exerts a force exceeding the compressive force provided by the spring 72.

When the latching device 20 is detached from the switching device 10 the spring 106 causes the lever 104 to be rotated to a position wherein the arm 108 engages the bottom surface 110. As the force provided by the, spring 106 exceeds the compressive force of the spring 72, the lever 104 will rotate in a clockwise direction and move the armature 54 and the plunger 56 upwardly and thereby rotate the latching lever 38 counterclockwise to 21 released position wherein the latching surface 70 is dis engaged from the latching surface 90. When the latching device 20 is initially positioned on the top end 18 of the switching device 10, the free end 88 will engage the end 26 of the contact carrier 22 and as the compressive force of the spring 94 is less than the force which urges the contact carrier 22 upwardly, the latching member 36 will be moved upwardly to a released position. Thus the contacts of the switching device 10 will be separated and in a circuit opening position. Further, as the latch device 20 is positioned on the top end 18, the arm portion 112 will engage the top surface of the end 18 and cause the lever 104 to rotate in a counterclockwise direction to an inoperative position which will permit the armature to assume the de-energized position as shown in FIG. 2. When the latching device 20 is applied to the switching device and the latching member 36 is moved upwardly, the latch surface 70 will be positioned adjacent the vertical surface 92 prior to the movement of the release means 100, including the lever 104, to an inoperative position so that the latching device 20 will remain in the released position after initial installation of the switching device 10 so that the latching device 20 may function in the normal manner, as heretofore explained.

While the latching device 20 herein disclosed has been explained as being used with a switching device disclosed in the Gribble et al. patent, it is obvious the latching device may be used with other types of switching devices. Further, the released mechanism as herein disclosed may be modified to be used with other types of latching mechanisms which are attachable to basic switching devices to prevent the latching mechanism from holding the components of the basic switching device in a latched position when the latching device is initially installed on the switching device.

While certain preferred embodiments of the invention have been specifically disclosed, it is understood that the invention is not limited thereto, as many variations will be readily apparent to those skilled in the art and the invention is to be given its broadest possible interpretation within the terms of the following claims.

What is claimed is:

1. An electromagnetically operated latching device for releasably maintaining a movable operating member of an electromagnetically operated switching device in a predetermined position, said latching device comprising: a housing having an end mountable on an end of the switching device, a guideway in the housing aligned with the operating member when the housing is mounted on the switching device, a latching member movable between a released position and a latching position in the guideway, a spring constantly urging the latching membertoward the latching position, a latching lever movable between a released position and a latching position, a spring constantly urging the latching lever toward the latching position, cooperating latching surfaces on the latching member and the latching lever for maintaining the latching member against movement from the latching position to the released position when the latching member and the latching lever are at their respective latching positions, an electromagnet in the housing, said electromagnet having an electrical coil, a magnet core adapted to be magnetized upon energization of the coil and an armature normally spaced from the core and adapted to be moved into engagement with the core upon energiza-' tion of the coil, a means for moving the latching lever to the released position upon movement of the armature into engagement with the core and a means operative only when the latching device is detached from the switching device for causing the latching lever to be moved to the released position.

2. The latching device as recited in claim 1 wherein the means for causing the latching lever to be moved to the released position when the latching device is detached from the switching device includes a releasing lever having a portion engaging the armature and a spring for moving the releasing lever to a position wherein the latching lever is moved to its released position.

3. The latching device as recited in claim 2 wherein the releasing lever includes a portion that engages portions on the end of the switching device for moving the releasing lever to an inoperative position when the housing is attached to the end of the switching device.

4. The latching device as recited in claim 1 wherein the latching lever includes a portion that is externally accessible through an opening in the housing for visually indicating the position of the latching lever in the housing and providing an accessible portion whereby the latching lever may be manually moved to the released position.

5. The latching device as recited in claim 3 wherein the latching lever includes a portion that is externally accessible through an opening in the housing for visually indicating the position of the latching lever in the housing and providing an accessible portion whereby the latching lever may be manually moved to the released position.

6. The latching device an recited in claim 1 wherein the latching member is linearly movable along an axis perpendicular to the end of the switching device and is axially aligned with the operating member.

7. The latching device as recited in claim 1 wherein a member carried by the armature engages a portion of the latching lever moves the latching lever to the released position upon movement of the armature toward the core.

8. The latching device as recited in claim 7 wherein the means for causing the latching lever to be moved to the released position when the latching device is detached from the switching device includes a releasing lever having a portion engaging the armature and a spring for moving the releasing lever to a position wherein the latching lever is moved to its released position.

9. The latching device as recited in claim 8 wherein the releasing lever includes a portion that engages portions on the end of the switching device for moving the releasing lever to an inoperative position when the housing is attached to the end of the switching device.

10. The latching device as recited in claim 9 wherein the latching lever includes a portion that is externally accessible through an opening in the housing for visually indicating the position of the latching lever in the housing and providing an accessible portion whereby the latching lever may be manually moved to the released position.

11. A latching device as recited in claim 1 wherein the means for causing the latching lever to be moved to the released position when the latching device is detached from the switching device includes a releasing lever and a spring, the spring being operative when the latching device is detached from the switching device to move the releasing lever to an operative position wherein the latching device is held in its released position, the releasing lever having a portion which, when the housng is attached to the end of the switching device, engages the switching device thereby to move the releasing lever to an inoperative position.

References Cited UNITED STATES PATENTS 3,076,074 1/1963 Landow 335-427 3,364,450 1/1968 Conner 335170 BERNARD A. GILHEANY, Primary Examiner H. BROOME, Assistant Examiner Patent No. 3,50 1,72l Dated March 17, 1970 Invent fl Adolfo M. Perez It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as 'shown below:

Col. 1, line 55, cancel "to the basic switching unit to maintain the contacts in basic'switch to be held" and insert. --to the basic switching unit, causes the contacts of the basic switch'to be held- 7 G01. --5,*1ine 30-,Rfor "latch" read -1atching.

SIGNED A'Nu SEALED JUL 211970 SEAL Altest:

- WILLIAM 1:. sum.

Edward M 171 I tomiss loner of Fahd ug Offlcu PO-wsd UNITED STATES PATENT OFFICE 

